Each year hundreds of thousands of people are afflicted with vascular diseases, such as arteriosclerosis, that result in cardiac ischemia. For more than thirty years, such disease, especially of the coronary arteries, has been treated using open surgical procedures, such as coronary artery bypass grafting. During such bypass grafting procedures, a sternotomy is performed to gain access to the pericardial sac, the patient is put on cardiopulmonary bypass, and the heart is stopped using a cardioplegia solution.
More recently, techniques are being developed, for example, by Heartport, Inc., Redwood City, Calif., that permit cardiac surgery using an endoscopic approach, in which small access openings are created between the ribs. The bypass graft or heart valve repair procedure is performed guided by an image displayed on a video monitor. In the "keyhole" techniques developed by Heartport, the patient's heart is stopped and the patient is placed on cardiopulmonary bypass. Still other techniques being developed, for example, by CardioThoracic Systems, Inc., of Cupertino, Calif., enable such bypass graft procedures to be performed on a beating heart.
In those techniques that involve stopping the heart to perform surgery, blood flow to the heart is occluded, for example, by placing occlusion balloons in the ascending aorta and/or the vena cava. Venous blood is then withdrawn from the patient, for example, from the vena cava, and oxygenated using an extracorporeal oxygenation circuit. The oxygenated blood is perfused into the patient in the vicinity of the aortic arch to provide oxygenated blood to the brain, internal organs and extremities.
U.S. Pat. No. 5,312,344 to Grinfeld et al. describes a multi-lumen perfusion catheter for perfusing oxygenated blood into a patient on cardiopulmonary bypass. The catheter has a distal balloon for occluding the ascending aorta, a first lumen for delivering cardioplegia solution through a first opening distal to the balloon, and a second lumen for perfusing oxygenated blood through a second opening proximal to the balloon. The catheter may be positioned in the ascending aorta either intraoperatively through an opening in the aorta, or in a retrograde manner via a femoral artery and the abdominal aorta.
One drawback associated with recently developed keyhole methods of cardiac surgery is that the surgeon often has only limited room in which to maneuver. This, in turn, may render previously known apparatus too cumbersome to be effectively used in conjunction with such techniques. Thus, for example, while the intraoperative version of the catheter described in the foregoing patent to Grinfeld et al. may be used instead of a cross-clamp where a sternotomy has been performed, the device may be less useful when keyhole surgical techniques are employed.
Specifically, intraoperative placement of the foregoing catheter involves placing a purse-string suture surrounding the arteriotomy, to prevent excessive blood loss. Because there may be insufficient room in which to form a purse string suture in a keyhole-type procedure, the surgeon may be unable to provide a tight seal around the entry point of the catheter.
It therefore would be desirable to provide apparatus and methods for delivering oxygenated blood to a patient from a cardiopulmonary bypass machine that overcome the drawbacks of previously known perfusion catheters.
It further would be desirable to provide apparatus and methods that enable a perfusion catheter to be positioned in the aorta via a sutureless arteriotomy.
A number of devices and methods have been developed to provide sutureless anastomoses. U.S. Pat. Nos. 4,366,819 and 4,368,736, both to Kaster, describe assemblies that provide sutureless anastomosis of a bypass graft by capturing the graft material between an interior flange and an exterior ring. U.S. Pat. No. 4,352,358 to Angelchik describes an anastomosis device formed from a tubular elastic membrane that is expanded on either side of the entry wound to provide a sutureless seal. None of these previously known devices appear suitable, without extensive modification, for providing a temporary sutureless arteriotomy for a perfusion catheter.
U.S. Pat. No. 5,167,628 to Boyles describes a catheter for isolating the coronary ostium between two toroidal-shaped balloons. The catheter includes a lumen enabling blood to pass from the left ventricle to the ascending aorta, while the balloons define a chamber into which treatment material may be provided to the coronary arteries. The patent describes that the balloons are spaced apart so that the lower balloon is disposed beneath the aortic valve in the left ventricle and the upper balloon is positioned distal of the coronary arteries.
In view of the foregoing, it would be desirable to provide apparatus and methods for delivering oxygenated blood to a patient from a cardiopulmonary bypass machine using sealing members that provide a sutureless arteriotomy, with little or no blood leakage.
It further would be desirable to provide apparatus and methods for occluding the aorta and for providing cardioplegia solution to the aortic root using a perfusion catheter inserted via a sutureless arteriotomy.